The role of elemental oxygen demand in total oxygen demand for water pollutants

For an advanced evaluation of water pollutants, EOD (elemental oxygen demand) was proposed, and the relation between EOD and TOD (total oxygen demand) was discussed. The EOD was defined as the oxygen demands of each element in the pollutants. A generalized equation of combustion reaction for compounds was proposed. The observed TOD values of various organic and inorganic compounds, except a few inorganic compounds, showed good agreement with the theoretical values calculated from the equation, and the TOD value was the summation of the amounts of EOD by each constituent element. The degrees of COD (carbon oxygen demand), EOD of carbon, and NOD (nitrogen oxygen demand), EOD of nitrogen, in TOD were investigated by using several organic compounds. The ratios of COD/TOD and NOD/TOD were generally above 0.5 and below 0.25, respectively. In an activated sludge pilot plant, the ratio of COD/TOD in influent was 0.76 and that of NOD/TOD 0.075; and in effluent, the NOD/TOD value was larger than the COD/TOD value.     

Benchmark analysis on PFM analysis codes for aged piping of nuclear power plants

Probabilistic fracture mechanics is a rational methodology in structural reliability evaluation and risk assessment for aged piping in nuclear power plants. Several probabilistic fracture mechanical analysis codes have been improved or developed in Japan. To verify the reliability and applicability of two of these codes, we did a benchmark analysis using their basic functions in consideration of representative piping systems in nuclear power plants and typical aging mechanisms. Based on the analysis results, we concluded that the analysis results of these two codes are in good agreement.     

System development and analysis for producing high quality gas and activated sludge char

For energy and resource utilization of dried sewage sludge, an integrated system with in-line connection of pyrolysis gasifier, plasma reformer, and fixed bed adsorber was developed. The plasma reformer was set to improve producer gas yield by destructing tar released from the pyrolysis gasifier. The fixed bed adsorber filled with the sludge char produced from the pyrolysis gasifier was installed for adsorption of un-treated tar. The pyrolysis gasifier produced sludge char, tar and gas. The sludge char showed 98.1 m²/g of specific surface area and 63.49 Å of mean pore size, which had a good distribution of micropore and mesopore with superior adsorption rate of light PAH tar. The concentrations of gravimetric tar and total light tar were 26.3 g/Nm³ and 10.9 g/Nm³, respectively. The analyzed light tar was in the order of benzene, naphthalene, benzonitrile, benzeneacetonitrile, anthracene and pyrene. Produced gas was composed of hydrogen, carbon monoxide, methane, and carbon dioxide. The plasma reformer displayed 83.2% of removal efficiency with 4.4 g/Nm³ of gravimetric tar at the outlet due to tar cracking and steam reforming reaction. The total amount of light tar was 1.3 g/Nm³. Among the reforming gas, the concentration of hydrogen, carbon monoxide, and methane was increased. Gravimetric tar at the outlet of the adsorber was 0.5 g/Nm³, which was 88.6% of removal efficiency. The total amount of light tar was 0.39 g/Nm³. Gas analysis results at the exit showed 50.5% H₂, 21.9% CO, 10.5% CH₄, 7.7% CO₂ and 0.1% C₂H₂ with a higher heating value of 13,482 kJ/Nm³. Therefore, sewage sludge can be converted into energy and resource by pyrolysis and gasification since the producer gas and sludge char could be utilized in a heat engine and adsorption tower for tar removal, respectively.

     

Solid circulation rate in a circulating fluidized bed in the presence of fine powders

Fine powders (Geldart's group C) are added to a circulating fluidized bed (CFB) of coarse particles (Geldart's group A) and the solid circulation rate (SCR) is investigated with addition of fine powders of different sizes and different fractions (different hold-ups) to the bed. Experiments were carried out in a CFB of 2 m in height and 0.052 m in diameter, using FCC catalyst particles of as the coarse particles and cohesive aluminum hydroxide powders of 0.5- as the fine powders. The effects of hold-up of fine powders in the bed, fine powders size, and superficial gas velocity on the SCR were investigated.The SCR strongly depended on the hold-up of fine powders of 0.5- in size and noticeably decreased with increasing the hold-up of fine powders under constant gas velocity. This dependency disappeared when the size of fine powders was larger than . Thus, depending on the size of fine powders added to the CFB, two distinct regions for the changes of SCR could be clearly identified.     

Rheological and Morphological Comparison of Thermal and Hydrostatic Pressure-Induced Filamentous Myosin Gels

The structure and rheological properties of heat‐ and pressure‐induced myosin filament gels were investigated. The apparent elasticity of heat‐induced gel peaked at 55 °C (4.35 ± 0.57 kPa), whereas that of pressure‐induced gel increased with elevating pressure, and the gel formed at 500 MPa had a value of 4.79 ± 0.25 kPa. All pressure‐ and heat‐induced gels showed similar internal structure, namely, the gels were composed of a fine‐strand network. The detailed structures of the strands induced by pressure‐ and heat‐treatment of myosin filaments were observed using an atomic force microscope. The structural differences among the strands were not observed, whereas the elasticity of the strands measured by atomic force microscope revealed differences among the strands formed with varying heating temperature and pressure. The elasticities of the heat‐induced strands were 1.19 ± 0.09 MPa, 10.24 ± 1.16 MPa, and 3.09 ± 0.25 MPa at 40 °C, 55 °C, and 70 °C, respectively. On the other hand, the elasticity of the pressure‐induced strand increased with elevating pressure. The elasticity values were 1.24 ± 0.09 MPa, 2.32 ± 0.17 MPa, and 9.80 ± 0.84 MPa at pressures of 150, 300, and 500 MPa, respectively. Because the changes in the elasticity of the whole gel corresponded to those of the strand, it is concluded that the rheological properties of the constituting strands determine that of myosin filamentous gel.     

Tracking and readout characteristics of a minute aperture mounted optical head slider flying above a chromium patterned medium

Recent rapid progress in a digital network society necessitates storage devices with higher-density and faster transfer rates. In optical storage, a novel recording principle is eagerly awaited that will drastically improve recording density without being restricted by a wavelength shortening limit or a numerical aperture (NA) limit of the optics utilized. Storage based on the “near-field” principle is thought to be one of the most promising breakthroughs for overcoming various limitations governing traditional optical recording. We have already proposed an integrated optical head slider assembly that relies on the novel near-field principle for its operation; it is mounted on a minute tapered aperture and has a planar focusing lens and a micro silicon mirror. Readout signals corresponding to a 200-nm-long bit have demonstrated a frequency band up to approximately 10 MHz, using a chromium patterned medium. In this study, we have investigated the accuracy of the tracking characteristics of an aperture-mounted head slider by using linearly arranged 1-mm-long line-and-space patterns. Based on the step or inverse step responses that occur when an aperture flies obliquely across the linearly arranged pattern region boundary, we present a simple method of predicting accurate tracking characteristics in detail, and also by using a 350-nm line-and-space pattern signal, we were able to predict both tracking characteristics and tracking sensitivities of arbitrary wide tracks to a track width of 100 nm.     

耐热/耐磨烧结合金发展趋势

粉末冶金的一个特殊优势是合金设计自由度高,因此,烧结合金广泛用于耐热与耐磨零件.主要产品对象是气门导管、阀座圈(VSI)及发动机排气系统的零件.近年来,为回应环境问题,发动机的使用性能在不断提高,这些零件的使用环境随之越益严苛,因此,就日益要求改进材料的耐磨性与其它性能.论述了近年来耐热／耐磨烧结材料的技术发展趋势,特...